9 Important Functions Of Protein In Your Body.docx

9 Important Functions of Protein in Your Body Protein is crucial to good health. In fact, the name comes from the Greek word proteos, meaning “primary” or “first place.” Proteins are made up of amino acids that join together to form long chains. You can think of a protein as a string of beads in which each bead is an amino acid. There are 20 amino acids that help form the thousands of different proteins in your body. Proteins do most of their work in the cell and perform various jobs. Here are 9 important functions of protein in your body.

1. Growth and Maintenance Your body needs protein for growth and maintenance of tissues. Yet, your body’s proteins are in a constant state of turnover. Under normal circumstances, your body breaks down the same amount of protein that it uses to build and repair tissues. Other times, it breaks down more protein than it can create, thus increasing your body’s needs. This typically happens in periods of illness, during pregnancy and while breastfeeding. People recovering from an injury or surgery, older adults and athletes require more protein as well. SUMMARY Protein is required for the growth and maintenance of tissues. Your body’s protein needs are dependent upon your health and activity level. 2. Causes Biochemical Reactions Enzymes are proteins that aid the thousands of biochemical reactions that take place within and outside of your cells. The structure of enzymes allows them to combine with other molecules inside the cell called substrates, which catalyze reactions that are essential to your metabolism. Enzymes may also function outside the cell, such as digestive enzymes like lactase and sucrase, which help digest sugar. Some enzymes require other molecules, such as vitamins or minerals, for a reaction to take place. Bodily functions that depend on enzymes include: 

Digestion

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Energy production

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Blood clotting

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Muscle contraction Lack or improper function of these enzymes can result in disease. SUMMARY Enzymes are proteins that allow key chemical reactions to take place within your body. 3. Acts as a Messenger Some proteins are hormones, which are chemical messengers that aid communication between your cells, tissues and organs. They’re made and secreted by endocrine tissues or glands and then transported in your blood to their target tissues or organs where they bind to protein receptors on the cell surface. Hormones can be grouped into three main categories (11):

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Protein and peptides: These are made from chains of amino acids, ranging from a few to several hundred.

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Steroids: These are made from the fat cholesterol. The sex hormones, testosterone and estrogen, are steroid-based.

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Amines: These are made from the individual amino acids tryptophan or tyrosine, which help make hormones related to sleep and metabolism. Protein and polypeptides make up most of your body’s hormones. Some examples include:

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Insulin: Signals the uptake of glucose or sugar into the cell.

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Glucagon: Signals the breakdown of stored glucose in the liver.

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hGH (human growth hormone): Stimulates the growth of various tissues, including bone.

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ADH (antidiuretic hormone): Signals the kidneys to reabsorb water.

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ACTH (adrenocorticotropic hormone): Stimulates the release of cortisol, a key factor in metabolism.

SUMMARY Amino acid chains of various lengths form protein and peptides, which make up several of your body’s hormones and transmit information between your cells, tissues and organs.

4. Provides Structure Some proteins are fibrous and provide cells and tissues with stiffness and rigidity. These proteins include keratin, collagen and elastin, which help form the connective framework of certain structures in your body (13). Keratin is a structural protein that is found in your skin, hair and nails. Collagen is the most abundant protein in your body and is the structural protein of your bones, tendons, ligaments and skin (14). Elastin is several hundred times more flexible than collagen. Its high elasticity allows many tissues in your body to return to their original shape after stretching or contracting, such as your uterus, lungs and arteries (15). SUMMARY A class of protein known as fibrous protein provides various parts of your body with structure, strength and elasticity. 5. Maintains Proper pH Protein plays a vital role in regulating the concentrations of acids and bases in your blood and other bodily fluids. The balance between acids and bases is measured using the pH scale. It ranges from 0 to 14, with 0 being the most acidic, 7 neutral and 14 the most alkaline. Examples of the pH value of common substances include: 

pH 2: Stomach acid

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pH 4: Tomato juice

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pH 5: Black coffee

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pH 7.4: Human blood

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pH 10: Milk of magnesia

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pH 12: Soapy water A variety of buffering systems allows your bodily fluids to maintain normal pH ranges. A constant pH is necessary, as even a slight change in pH can be harmful or potentially deadly (19, 20). One way your body regulates pH is with proteins. An example is hemoglobin, a protein that makes up red blood cells. Hemoglobin binds small amounts of acid, helping to maintain the normal pH value of your blood.

The other buffer systems in your body include phosphate and bicarbonate. SUMMARY Proteins act as a buffer system, helping your body maintain proper pH values of the blood and other bodily fluids. 6. Balances Fluids Proteins regulate body processes to maintain fluid balance. Albumin and globulin are proteins in your blood that help maintain your body’s fluid balance by attracting and retaining water. If you don’t eat enough protein, your levels of albumin and globulin eventually decrease. Consequently, these proteins can no longer keep blood in your blood vessels, and the fluid is forced into the spaces between your cells. As the fluid continues to build up in the spaces between your cells, swelling or edema occurs, particularly in the stomach region. This is a form of severe protein malnutrition called kwashiorkor that develops when a person is consuming enough calories but does not consume enough protein. Kwashiorkor is rare in developed regions of the world and occurs more often in areas of starvation. SUMMARYProteins in your blood maintain the fluid balance between your blood and the surrounding tissues. 7. Bolsters Immune Health Proteins help form immunoglobulins, or antibodies, to fight infection. Antibodies are proteins in your blood that help protect your body from harmful invaders like bacteria and viruses. When these foreign invaders enter your cells, your body produces antibodies that tag them for elimination. Without these antibodies, bacteria and viruses would be free to multiply and overwhelm your body with the disease they cause. Once your body has produced antibodies against a particular bacteria or virus, your cells never forget how to make them. This allows the antibodies to respond quickly the next time a particular disease agent invades your body. As a result, your body develops immunity against the diseases to which it is exposed. SUMMARY

Proteins form antibodies to protect your body from foreign invaders, such as disease-causing bacteria and viruses. 8. Transports and Stores Nutrients Transport proteins carry substances throughout your bloodstream — into cells, out of cells or within cells. The substances transported by these proteins include nutrients like vitamins or minerals, blood sugar, cholesterol and oxygen. For example, hemoglobin is a protein that carries oxygen from your lungs to body tissues. Glucose transporters (GLUT) move glucose to your cells, while lipoproteins transport cholesterol and other fats in your blood. Protein transporters are specific, meaning they will only bind to specific substances. In other words, a protein transporter that moves glucose will not move cholesterol. Proteins also have storage roles. Ferritin is a storage protein that stores iron. Another storage protein is casein, which is the principal protein in milk that helps babies grow. SUMMARY Some proteins transport nutrients throughout your entire body, while others store them. 9. Provides Energy Proteins can supply your body with energy. Protein contains four calories per gram, the same amount of energy that carbs provide. Fats supply the most energy, at nine calories per gram. However, the last thing your body wants to use for energy is protein since this valuable nutrient is widely used throughout your body. Carbs and fats are much better suited for providing energy, as your body maintains reserves for use as fuel. Moreover, they’re metabolized more efficiently compared to protein. In fact, protein supplies your body with very little of its energy needs under normal circumstances. However, in a state of fasting (18–48 hours of no food intake), your body breaks down skeletal muscle so that the amino acids can supply you with energy. Your body also uses amino acids from broken-down skeletal muscle if carbohydrate storage is low. This can occur after exhaustive exercise or if you don’t consume enough calories in general. SUMMARY Protein can serve as a valuable energy source but only in situations of fasting, exhaustive exercise or inadequate calorie intake.

The Bottom Line Protein has many roles in your body. It helps repair and build your body’s tissues, allows metabolic reactions to take place and coordinates bodily functions. In addition to providing your body with a structural framework, proteins also maintain proper pH and fluid balance. Finally, they keep your immune system strong, transport and store nutrients and can act as an energy source, if needed. Collectively, these functions make protein one of the most important nutrients for your health. Proteins Proteins are important molecules in cells. Proteins are the major component of the dry weight of cells. The name protein is derived from a Greek word Proteios which means pre-eminent or first. This name was fist suggested in 1838 by a Swedish chemist Berzelius. He suggested it to a Dutch chemist Mulder and he referred it to the complex organic substances found in the cells of living beings. Proteins are the most abundant intracellular macro-molecules. Proteins are connected intimately with all chemical and physical activity, which constitutes the life of the cell. Proteins are present in and vital to all living cells. They provide structure, protection to the body of multicellular organism in the form of skin, hair, callus, cartilage, ligaments, muscles, tendons. Proteins regulate and catalyze the body chemistry in the form of hormones, enzymes, immunoglobulins etc. What are Proteins? Proteins are known as building blocks of life. Proteins are biomolecules, usually large in size, that consists of one or more chains of amino acids. Proteins perform variety of functions like catalyzing metabolic reactions, replication of DNA, response to stimuli, and transporting molecules. Proteins differ from each other mainly in the sequences of amino acids.

Characteristics of Proteins General Characteristics of Proteins are as follows: 

Proteins are organic substances; they are made up of nitrogen and also, oxygen, carbon and hydrogen.

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Proteins are the most important biomolecules, they are the fundamental constituent of the cytoplasm of the cell.

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Proteins are the structural elements of body tissues.

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Proteins are made up of amino acids.

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Proteins give heat and energy to the body and also aid in building and repair.

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Only small amounts of proteins are stored in the body as they can be used up quickly on demand.

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Proteins are considered as the bricks, they make up bones, muscles, hair and other parts of the body.

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Proteins like enzymes are functional elements that take part in metabolic reactions.

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Antibodies, blood hemoglobin are also made of proteins.

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Proteins have a molecular weight of 5 to 300 kilo-Daltons.

Properties of Proteins The general properties of proteins are similar to those of the amino acids:

Physical Properties of Proteins 

Proteins are colorless and tasteless.

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They are homogeneous and crystalline.

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Proteins vary in shape; they may be simple crystalloid structure to long fibrilar structures.

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Protein structures are of two distinct patterns - Globular proteins and fibrilar proteins.

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Globular proteins are spherical in shape and occur in plants. Fibrilar proteins are thread-like, they occur generally in animals.

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In general proteins have large molecular weights ranging between 5 X 103 and 1 X 106.

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Due to the huge size, proteins exhibit many colloidal properties.

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The diffusion rate of proteins is extremely slow.

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Proteins exhibit Tyndall effect.

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Proteins tend to change their properties like denaturation. Many a times the process of denaturation is followed by coagulation.

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Denaturation may be a result of either physical or chemical agents. The physical agents include, shaking, freezing, heating etc. Chemical agents are like X-rays, radioactive and ultrasonic radiations.

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Proteins like the amino acids exhibit amphoteric property i.e., they can act as acids and alkalies.

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As the proteins are amphoteric in nature, they can form salts with both cations and anions based on the net charge.

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The solubility of proteins depends upon the pH. Lowest solubility is seen at isoelectric point, the solubility increases with increase in acidity or alkalinity.

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All the proteins show the plane of polarized light to the left, i.e., laevorotatory.

Chemical Properties of Proteins 

Proteins when hydrolyzed by acidic agents, like conc.HCl yield amino acids in the form of their hydrochlorides.

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Proteins when are hydrolyzed with alkaline agents leads to hydrolysis of certain amino acids like arginie, cysteine, serine, etc., also the optical activity of the amino acids is lost.

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Proteins with reaction with alcohols give its corresponding esters. This process is known as esterification.

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Amino acids react with amines to form amides.

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When free amino acids or proteins are said to react with mineral acids like HCl, the acid salts are formed.

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When amino acid in alkaline medium reacts with many acid chlorides, acylation reaction takes place.

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Sanger's reaction - Proteins react with FDNB reagent to produce yellow colored derivative, DNB amino acid.

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Xanthoproteic test - On boiling proteins with conc. HNO3, yellow color develops due to presence of benzene ring.

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Folin's test - This is a specific test for tyrosine amino acid, where blue color develops with phosphomolybdotungstic acid in alkaline solution due to presence of phenol group.

Protein Classification Classification of Proteins Based on Shape They are grouped under two categories globular and fibrous. Globular or Corpuscular Proteins Globular proteins have axial ratio less than 10. They are compactly folded and coiled. and possess a relatively spherical or ovoid shape. They are usually soluble in water and in aqueous media. Example: Insulin, plasma albumin, globulin enzymes. Fibrous or Fibrillar Proteins

These proteins have axial ratio more than 10, hence, they resemble long ribbons or fibres in shape. They are mostly found in animals, and are not soluble in water or in solution of dilute acids. Fibrous proteins aid in protection and structural support. Example: Collagen, Keratin, Elastins, Fibroin.

Classification of Proteins Based on Composition and Solubility Simple Proteins or Holoproteins These proteins are made of only one type of amino acid, as structural component, on decomposition with acids, they liberate constituent amino acids. They are mostly globular type of proteins except for scleroproteins, which are fibrous in nature. Simple proteins are further classified based on their solubility. Protamines and histones - These proteins occur only in animals and are basic proteins. The possess simple structure and low molecular, are water soluble and are not coagulated by heat. The are strongly basic in character due to the high content of lysine, arginine. Example: Protamines - salmine, clupine, cyprinine; Histones - nucleoshistones, globin. Albumins - They are widely distributed in nature, mostly seen in seeds. They are soluble in water and dilute solutions of acids, bases and salts. Example: Leucosine, legumeline, serum albumin. Globulins - They are of two types, pseudoglobulins which are soluble in water, other is euglobulins which are insoluble in water. They are coagulated by heat. Example: Pseudoglobulin, serum globulin, glycinine. etc. Scleroproteins or Albuminoids - These occur mostly in animals and are commonly known as animal skeleton proteins, they are insoluble in water, and in dilute solution of acids, based and salts. Conjugated or Complex Proteins or Heteroproteins These are proteins that are made of amino acids and other organic compounds. The non-amino acid group is termed as prosthetic group. Complex proteins are further classified based on the type of prosthetic group present. Metalloproteins - These are proteins linked with various metals. Example: casein, collagen, ceruloplasmin, etc. Chromoproteins - These are proteins that are coupled with a colored pigment. Example: Myoglubin, hemocyanin, cytochromes, flavoproteins, etc. Glycoproteins and Mucoproteins - These proteins contain carbohydrates as the prosthetic group. Example: Glycoproteins - egg albumin, serum globulins, serum albumins; Mucoproteins Ovomucoid, mucin etc. Phosphoproteins - These proteins are linked with phosphoric acid. Example: casein.

Lipoproteins - Proteins forming complexes with lipids are lipoproteins. Example: lipovitellin, lipoproteins of blood. Nucleoproteins - These are compounds containing nucleic acids and proteins. Example: Nucleoproteins, nucleohistones, nuclein.

Derived Proteins These are proteins that are derived from the action of heat, enzyme or chemical reagents. Derived proteins are of two types, primarily derived proteins and secondary derived proteins. Primary derived proteins are derivatives of proteins, in which the size of the protein molecule is not altered materially, while in secondary derived proteins, hydrolysis occurs, as a result the molecules are smaller than the original proteins. Primary derived proteins are classified into three types - Proteans, Infraproteins and Coagulated proteins. Example: edestan, coagulated eggwhite. Secondary derived proteins are further classified into 3 types - Proteoses, Peptones and Polypeptides. Classification of Proteins on Biological Function Proteins depending upon their physical and chemical structure and location inside the cell, they perform various functions. Proteins are grouped as follows, based on their metabolic function they perform. Enzymic Proteins They are the most varied and highly specialized proteins with catalytic activity. Enzymes catalyze a variety of reactions. Example: Urease, catalase, cytochrome C, etc. Structural Proteins Theses proteins aid in strengthening or protecting biological structures. Example: Collagen, elastin, keratin, etc. Transport or Carrier Proteins These proteins help in transport of ions or molecules in the body. Example: Myoglobin, hemoglobin, etc. Nutrient and Storage Proteins These proteins provide nutrition to growing embryos and store ions. Contractile or Motile Proteins These proteins function in the contractile system. Example: Actin, myosin, tubulin, etc. Defense Proteins These proteins defend against other organisms. Example: Antibodies, Fibrinogen, thrombin. Regulatory Proteins They regulate cellular or metabolic activities. Example: Insulin, G proteins, etc. Toxic Proteins These proteins hydrolyze or degrade enzymes. Example: snake venom, ricin.

Structure of Proteins There are four structural levels of organization to describe the complex macromolecule, protein based on the degree of complexity of of the molecule. They are Primary Structure, Secondary structure, Tertiary structure and Quaternary structure. Primary Structure of Protein 

Primary structure of protein is the linear sequence of amino acids that make up the polypeptide chain.

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his sequence is given by the sequence of nucleotide bases of the DNA in the genetic code.

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The amino acid sequence determines the positioning of the different R groups relative to each other.

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The positioning determines the way the protein folds and the final structure of the molecule.

Secondary Structure of Protein 

The linear, unfolded structure of polypeptide chain assumes helical shape to produce the secondary structure.

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The secondary structure refers to the regular folding pattern of twists and kinks of the polypeptide chain.

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The regular pattern is due to the hydrogen bond formation between atoms of the amino acid backbone of the polypeptide chain.

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The most common types of the secondary structure are the alpha helix and the ß pleated sheet.

Tertiary Structure of Protein 

Tertiary structure of proteins is the three dimensional structure formed by the bending and twisting of the polypeptide chain.

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The linear sequence of polypeptide chain is folded into compact globular structure.

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The folding of the polypeptide chain is stabilized by weak, noncovalent interactions.

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These interactions are hydrogen bonds and electrostatic interactions.

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Hydrogen bonds are formed when hydrogen atom is shared with two other atoms.

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Electrostatic interactions between charged amino acid chains.

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Electrostatic interactions are between positive and negative ions of the macromolecules.

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Hydrophobic interactions, disulphide linkages and covalent bonds also contribute to tertiary structure.

Quaternary Structure of Protein 

Some proteins contain more than one polypeptide chains, this association of polypeptide chains refers to the quaternary structure.

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Each polypeptide chain is called a subunit.

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The subunits can be same or different ones.

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Example: Haemoglobin the oxygen carrying component of blood is made up of two polypeptide chains, one with 141 amino acids and the other is a different type of 146 amino acids. Function of Proteins

Below is the list of proteins functions. 

Proteins are seen in muscles, hair, skin and other tissues; they constitute the bulk of body's nonskeletal structure. Example: The protein keratin is present in nails and hair.

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Some proteins are hormones and regulate many body functions. Example: Insulin hormone is a protein and it regulated the blood sugar level.

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Some proteins act enzymes, they catalyze or help in biochemical reactions. Example: Pepsin and Tripsin.

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Some proteins act as antibodies; they protect the body from the effect of invading species or substances.

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Proteins transport different substances in blood of different tissues. Example: Hemoglobin is a oxygen transport protein.

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Contractile proteins help in contraction of muscle and cells of our body. Example: Myosin is contractile protein.

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Fibrinogen a glycoprotein helps in healing of wounds. It prevents blood loss and inhibits passage of germs. Types of Proteins

The types of proteins are as follows: 

Hormones are the proteins based chemicals that are secreted by the endocrine glands. Hormones are chemical messengers that transmit signals from one cell to the other.

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Enzymatic proteins accelerate the metabolic activity in the cells.

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Structural proteins are necessary components of the body. Structural proteins like collagen forms connective framework in body tissues, and keratin is main component of hair, skin and nails.

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Defensive proteins like antibodies and immunoglobulin are the core part of the body's immune system.

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Storage proteins store mainly mineral ions in the body, like potassium, iron etc.

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Transport proteins carry vital materials to the cells.

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Receptor proteins are located on the outer part of the cells, they control the substances that leave and enter the cell.

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Contractile proteins control the strength and speed of heart and muscle contractions. Examples of Proteins

Examples of fibrous proteins: Actin, Collagen, Elastin, Fibronectin, Keratin, Myosin, Tropomyosin, Tubulin, etc Examples of globular proteins: Albumins, Alpha globulin, Beta globulin, Cadherin, Fibrin, Gamma globulin, Haemoglobin, Immunoglobins, Myoglobin, Selectin, Serum albumin, Thrombin etc. Examples of membrane proteins: Estrogen receptor, Glucose transporter, Histones, Hydrolases, Oxidoreductases, P53, Rhodopsin, etc.

What Are the Main Functions of Minerals in the Body? Minerals are essential nutrients found in many different types of plant- and animal-based foods. Macro-minerals, or those you require in greater amounts, include calcium, potassium, sodium, phosphorus, magnesium, chloride, and sulfur. Trace minerals, or those you need in smaller amounts, include iron, zinc, selenium, manganese, copper, iodine, cobalt, and fluoride. Both types of minerals support a wide variety of bodily functions, ranging from building and maintaining healthy bones and teeth to keeping your muscles, heart and brain working properly. Bone and Tooth Health Your skeleton provides motility, protection and support for the body. It also stores minerals and other nutrients. Though they appear hard and unyielding, your bones are actually constantly being reabsorbed and reformed by your body. Several minerals make up the lattice architecture of your bones. Calcium is the most abundant mineral in your body and is found in your bones and blood. Along with the minerals phosphorus and magnesium, calcium gives your bones strength and density. This mineral also builds and maintains strong, healthy teeth. Calcium deficiency due to poor nutrition or illness can lead to osteoporosis, a condition in which the bones become brittle and less dense, increasing the risk of fractures. KidsHealth notes that foods that are rich in calcium include milk and other dairy products, green, leafy vegetables and canned fish with bones. Energy Production You require oxygen to produce energy that is necessary for every bodily function and process. Red blood cells -- or erythrocytes -- carry oxygen to each of your infinite cells, where it is used to generate energy. Red blood cells contain a heme or iron component that binds to oxygen so that it can be transported. Without the iron molecules, oxygen could not be attached to the blood cells and the body would not be able to produce the energy necessary for life. Iron is an essential mineral, and failing to get enough from your diet can lead to a condition called anemia, which causes weakness and fatigue. This mineral is primarily found in the blood, and it is also stored in your liver, spleen, bone marrow and muscles. Nerve and Muscle Function Potassium is found in bananas, dates, tomatoes, green leafy vegetables, citrus fruits and legumes such as peas and lentils. This nutrient is important to keep muscles and the nervous system functioning normally. Potassium helps to maintain the correct water balance in the cells of your nerves and muscles. Without this essential mineral, your nerves could not generate an impulse to signal your body to move, and the muscles in your heart, organs and body would not be able to contract and flex.

Immune Health Some minerals such as calcium are needed in large quantities, while others such as zinc are only needed in trace amounts. Zinc is an essential mineral that is important for keeping your immune system strong and helps your body fight infections, heal wounds and repair cells. KidsHealth notes that eating meat and legumes such as beans, peas and lentils will give you sufficient amounts of zinc. Selenium is also needed in small amounts for immune health. A deficiency of selenium has been linked to an increased risk of heart disease and even some types of cancers.